A 2005 review of 14 studies on IBS hypnotherapy, involving 644 people, concluded that it consistently improved symptoms in most patients. The six studies that used a control group--including hypnosis without any suggestion of pain relief--found improvement in 52 to 87 percent of patients.

The benefits of hypnotherapy seem to last, a 2003 British study found. The researchers surveyed 204 patients up to six years after hypnotherapy, which had initially helped over two-thirds of them. Of those positive responders, 81 percent maintained the improvement, with no significant drop-off as the years passed.

Hypnotherapists can't explain exactly how the technique works. While IBS is exacerbated by stress, it is not a purely psychological disorder, says Olafur Palsson, associate professor of medicine at the University of North Carolina and author of a widely used hypnosis protocol. "The current understanding of IBS suggests that there is a problem in the way the brain and the gut interact in controlling bowel function," he says.The hypnotic suggestions seem to "help make that normal again."

"Hypnosis eases irritable bowel syndrome" is from the October 2006 issue of Consumer Reports on Health.